1. Field of the Invention
The present invention relates to a liquid ejection head that performs a recording operation by ejecting liquid, a method of inspecting the liquid ejection head, and a liquid ejection apparatus including the liquid ejection head.
2. Description of the Related Art
Liquid ejection heads, such as inkjet recording heads, perform a recording operation by ejecting liquid from ejection ports. The ejection ports are provided in an ejection-port member provided on a liquid-ejection-head substrate having energy-generating elements that generate energy used for ejecting the liquid. The sizes of liquid droplets to be ejected greatly depend on the areas of openings of the ejection ports and therefore vary if the areas of openings vary, leading to unevenness in an image recorded on a recording medium.
Techniques of identifying the areas of openings of ejection ports without actually ejecting liquid droplets are disclosed by Japanese Patent Laid-Open No. 2002-154202 and Japanese Patent Laid-Open No. 2007-098701. A liquid ejection head disclosed by Japanese Patent Laid-Open No. 2002-154202 includes dummy ejection ports in addition to ejection ports used for ejection of liquid. By counting the number of pixels forming an image of each dummy ejection port, the areas of the openings of the ejection ports are estimated.
A liquid ejection head disclosed by Japanese Patent Laid-Open No. 2007-098701 is illustrated in FIG. 10 and includes a member 120. The member 120 has ejection ports 121 and channels 122. The member 120 is provided on a liquid-ejection-head substrate 114 having heat-generating elements 111. An exposure mask used in providing the ejection ports 121 has a plurality of slits of different widths near openings corresponding to the ejection ports 121. When exposure and development are performed on the member 120 with such an exposure mask, the ejection ports 121 and a plurality of slits 123 are provided in the member 120. By measuring the number of slits 123 and the widths of the slits 123, the diameters of the ejection ports 121 are estimated.
According to a review conducted by the present inventors, in the technique disclosed by Japanese Patent Laid-Open No. 2002-154202, an image of the liquid ejection head is read through a microscope, a processing operation of binarizing pixels of the read image is performed, and the pixels are counted. Therefore, it takes time to estimate the diameters of the openings of the ejection ports. Such a technique is not considered to be suitable for mass production.
Meanwhile, the technique disclosed by Japanese Patent Laid-Open No. 2007-098701 employs an indirect measurement method in which the shapes of the openings of the ejection ports are identified from the shapes of slits. In this case, however, factors affecting the shapes of the openings of the ejection ports do not necessarily affect the shapes of the slits in an exactly corresponding way. Therefore, it may be difficult to make accurate evaluation depending on the shapes of the ejection ports.